We have an amazing count of over 320 Insights published at Physics Forums. Now we test to see how much you remember from some of them. If you need a hint feel free to read the corresponding Insight which is linked at the end of the question. Good Luck and remember to read future Insights as there will be more hunts on the way! Don’t forget to add your score to the comments.

1. What paper won the Gravity Research Foundation essay contest in 1990? (link)

Building up spacetime with quantum entanglement

Monopoles and the Emergence of Black Hole Entropy

Gravity and the Nature of Fundamental Particles

Using Gravitational Lenses to Detect Gravitational Waves

2. Two observers watch a block slide down a frictionless incline under the influence of gravity from point A to point B. Observer 1 is at rest relative to the incline, but observer 2 is moving at constant horizontal velocity. Consider the following quantities:
I. Work done by the normal force on the block.
II. Work done by gravity on the block.
III. Total mechanical energy of the block.

Which of these quantities will have the same value according to the two observers? (link)

I only

II only

I and II

II and III

3. Which of the following is the only correct statement about irreversible processes applied to a system? (link)

For an adiabatic irreversible process, the change in entropy of the system is zero

Even for an irreversible process, there are an infinite number of reversible process paths between the initial and final thermodynamic equilibrium states of the system

You need to evaluate the integral of dq/T for the actual irreversible process path to get the entropy change

Entropy is not an equilibrium physical property of the materials comprising a system; it depends on the number of irreversible process paths that can be applied to the system

4. What is the predicted probability that a Higgs boson decays to b-quarks? (link)

7. From a scientific (as opposed to a popular) point of view, how do virtual particles get the energy needed to pop into existence? (link)

They take energy from the infinite supply of zero-point energy

They don’t need any energy because their existence is virtual only

They violate for a short time the conservation of energy

They rely on the Heisenberg uncertainty relation

8. Which lens aberration cannot be controlled by stopping down your lens? (link)

field curvature

coma

spherical aberration

distortion

9. Equal intervals of proper time for different observers can be represented by “clock diamonds” on a spacetime diagram. With the help of rotated graph paper, these clock diamonds are drawn with (link)

11. A long solenoid has ## n=500 \, turns/meter ## and has a DC current ## I=+1.0 ## amperes. The magnetic field ## B=n \mu_o I =6.28 E-4 \, Weber/m^2## inside the solenoid. A long cylindrical permanent magnet has (approximately) uniform magnetization pointing along the z-axis. Given the magnetic field strength ## B=1.0 \hat{z} \, Weber/m^2 ## inside the permanent magnet (i.e. in the interior, away from the endfaces), what is the magnetic surface current per unit length ## K_m ## on the outer surface of the cylindrical magnet? (Link)

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